Demand for integrated circuits (ICs) in portable electronic applications has motivated greater levels of semiconductor device integration. Many advanced semiconductor devices in development leverage non-silicon semiconductor materials, including compound semiconductor materials (e.g., GaAs, InP, InGaAs, InAs, and III-N materials). These non-silicon material systems may be employed in high electron mobility transistors (HEMT), some of which may be metal oxide semiconductor field effect transistors (MOSFET).
One technique for fabricating high electron mobility transistors includes forming a non-silicon crystalline device region (e.g., a transistor channel region) over a crystalline silicon substrate. One problem however is that silicon atoms from the underlying substrate can act as a contaminant within non-silicon device regions. Techniques and structures to mitigate the problem of silicon contamination are therefore advantageous in the fabrication of HEMTs on silicon substrates.